USPS first class mailing deadline is Tuesday

Slap a stamp on those Christmas cards. Tuesday is the cut-off day to send something first class via the U.S. Postal Service and have it delivered in time for Christmas.

According to the Postal Service, yesterday was the busiest shipping day of the year.

The post office is expected to process 750 million letters and packages for the Christmas holiday.

Tuesday is also the last day to ship via FedEx's Express Saver shipping option and have the package arrive before December 25.

Wednesday is the last day to ship an item via UPS 2nd Day Air and have it arrive before Christmas.